That scene where they get overwhelmed by the monsters was brutal, even though Kirito was overleveled enough to kill his opponents in one hit that was not enough to save Sachi. Such a cute girl gone so fast...that's not good at all.

I thought conquering SAO was all about linear progression and keep going up and up so it was nice to see Kirito actually had to backtrack to a lower floor in order to hunt the event boss. Another cool thing: changing his equipment before the battle (coat with +cold resist?).